Image caption, To find the mean age, use a calculator to divide the total age of all the children (168) by how many children there are (15). 168 ÷ 15 = 11.2. The mean age is 11.2 years old.

The mean is the most commonly used measure of average. To find the mean of a list of numbers, add them all together and divide by how many numbers there are: \(\text{mean} = \frac{\text{sum of all ...